Interspecific potato somatic hybrids between Solanum malmeanum and S. tuberosum provide valuable resources for freezing-tolerance breeding

Wei Tu,Jingwen Ying,Ying Zou,Xingkui Cai,Juan Du,Haibo Wang,Botao Song,Jianke Dong,Qinghao Zhao,Jianghai Wu

doi:10.1007/s11240-021-02106-2

Abstract

Freezing stress affects the geographic distribution, growth, and development of potato, resulting in yield loss. Solanum malmeanum, a diploid wild species with strong freezing tolerance, was fused with the freezing sensitive dihaploid S. tuberosum by somatic hybridization. In our study, 980 calli were obtained, and 248 differentiated shoots were obtained from the calli. Parental-specific SSR markers were used to analyse the chromosome composition of the 80 randomly selected regenerated plants, obtaining 51 somatic hybrids. Among them, 44 somatic hybrids were tested with ploidy analysis in the years 2016 and 2020. During subculture, the genomic ploidy levels changed due to the composition of the unstable chromosome in 56.82% of the somatic hybrids. The somatic hybrids showed better freezing tolerance than the cultivated parent. Then, freezing-tolerant somatic hybrids were selected to backcross with cultivars, and we obtained valuable breeding resources with enhanced freezing tolerance and tuberization capacity similar to that of cultivars. The correlation analysis showed that freezing tolerance has no relation with tuberization capacity, which indicates that they are controlled by independent genetic loci.

Highlights

Potato (Solanum tuberosum L.), the fourth food crop and the most important tuber crop in the world, is cultivated extensively for low fat and rich nutrition value and consumed by more than one billion people (Bradeen and Kole 2016; Haan and Rodriguez 2016)
The brown and dead shoots were removed during subculture, and in total 80 vigorous shoots with strong roots were used for the analysis of their ploidy and genetic constitution (Fig. 1)
51 regenerated plantlets were identified as somatic hybrids among 80 tested plantlets, which led to the successful protoplast fusion rate to 63.75%

Summary

Introduction

Potato (Solanum tuberosum L.), the fourth food crop and the most important tuber crop in the world, is cultivated extensively for low fat and rich nutrition value and consumed by more than one billion people (Bradeen and Kole 2016; Haan and Rodriguez 2016). It is significant to construct potato germplasm with freezing-tolerance by genetic modification. Wild potato species possess higher freezing tolerance, including non-acclimated freezing tolerance (NA) and cold acclimation freezing tolerance (CA) (Palta and Simon 1993; Palta 1994; Gray et al 1997; Seppänen et al 2008). More than 30 wild species, such as S. acaule, S. boliviense, S. chomatophilum, S. commersonii, and S. demissum, were reported to possess strong freezing tolerance (Ross and Rowe 1965; Li 1977; Vega and Bamberg 1995). Our previous freezing tests in a large number of wild species showed strong freezing tolerance in S. acaule, S. albicans, S. commersonii, S. demissum, and S. malmeanum, which all were significant germplasms for potato freezing-tolerant breeding

Methods

Results

Conclusion